15 Fakultätsübergreifend / Sonstige Einrichtung
Permanent URI for this collectionhttps://elib.uni-stuttgart.de/handle/11682/16
Browse
7 results
Search Results
Item Open Access Kapitel 7, Stofftransport im Grundwasser(1987) Kobus, Helmut; Geldner, PeterDie Nutzung des Grundwassers ist in der BRD vorranging der Trinkwasserversorgung vorbehalten. Die Zielvorstellung der Wasserversorgung ist es, Grundwasser möglichst naturbelassen und ohne Aufbereitung als Trinkwasser abzugeben. Hieraus resultiert die ungeschriebene Forderung, daß der Rohstoff Grundwasser die Qualitätsanforderungen an Trinkwasser erfüllen soll. Eine vorrangige Aufgabe der Grundwasserwirtschaft ist darin zu sehen, anthropogene Beeinträchtigungen der Grundwasserqualität zu erfassen und zu beurteilen. Die Frage nach den Auswirkungen von Schadensfällen setzt das Verständnis des Transports von Schadstoffen im Untergrund voraus. Dies ist umso wichtiger, wenn wasserwirtschaftliche Maßnahmen zur Schadensbegrenzung oder Schadensanierung geplant werden.Item Open Access Field testing of feedforward collective pitch control on the CART2 using a nacelle-based lidar scanner(2012) Schlipf, David; Fleming, Paul; Haizmann, Florian; Scholbrock, Andrew; Hofsäß, Martin; Wright, Alan; Cheng, Po WenThis work presents the first results from a field test to proof the concept of LIDAR assisted collective pitch control using a scanning LIDAR device installed on the nacelle of a research turbine. The purpose of the campaign was to show that a reduction of rotor speed variation is feasible with a feedforward update without changing the feedback controller. Although only a small amount of data could be collected, positive effects can be observed not only on the rotor speed but also on tower, blade and shaft loads in the case that the correlation of the wind preview and the turbine reaction is taken into account.Item Open Access Activity of lipases and esterases towards tertiary alcohols : new insights into structure-function relationships(2002) Henke, Erik; Pleiss, Jürgen; Bornscheuer, Uwe TheoHydrolytic enzymes are versatile biocatalysts and find increasing applications in organic synthesis and a considerable number of industrial processes using these enzymes have been commercialized. Within this class, lipases (E.C. 3.1.1.3) and carboxyl esterases (E.C. 3.1.1.1) are frequently used as they accept a broad range of non-natural substrates, are usually very stable in organic solvents and exhibit good to excellent stereoselectivity.Item Open Access Links between the personalities, styles and performance in computer programming(2015) Karimi, Zahra; Baraani-Dastjerdi, Ahmad; Ghasem-Aghaee, Nasser; Wagner, StefanThere are repetitive patterns in strategies of manipulating source code. For example, modifying source code before acquiring knowledge of how a code works is a depth-first style whereas reading and understanding before modifying source code is a breadth-first style. To the extent we know, there is no study on the influence of personality on them. The objective of this study is to understand the influence of personality on programming styles. We did a correlational study with 65 programmers at the University of Stuttgart. Academic achievement, programming experience, attitude towards programming, and five personality factors were measured via self-assessed survey. The programming styles were asked for in the survey or mined from the software repositories. Performance in programming was composed of bug-proneness of programmers which was mined from software repositories, the grades they got in a software project course and their estimate of their own programming ability. In a statistical analysis we found that Openness to Experience has a positive association with breadth-first style and Conscientiousness has a positive association with depth-first style. We also found that, in addition to having more programming experience and better academic achievement, the styles of working depth-first and saving coarse-grained revisions improve performance in programming.Item Open Access Selective hydroxylation of highly branched fatty acids and their derivatives by CYP102A1 from Bacillus megaterium(2006) Budde, Michael; Morr, Michael; Schmid, Rolf D.; Urlacher, Vlada B.Highly branched fatty acids, representing the main component of the preen gland wax of the domestic goose, and their derivatives are promising chiral precursors for the synthesis of macrolid antibiotics. The key step in utilisation of these compounds is the regioselective hydroxylation, which can not be done in a classical chemical approach. Three P450 monooxygenases CYP102A1, CYP102A2 and CYP102A3, demonstrating high turnover numbers in hydroxylation of iso and anteiso fatty acids (>400 min-1), were tested for their activity towards these substrates. CYP102A1 from Bacillus megaterium as well as its A74G F87V L188Q triple mutant hydroxylate a variety of these substrates with high activity and regioselectivity. In all cases the triple mutant showed much higher activities than the wild type enzyme. The binding constants, determined for CYP102A1 wild type and the triple mutant were >200 µM and ~23 µM, respectively, when tetramethyl nonanol was used as substrate. The data derived from binding analysis supports the differences in activity found for the CYP102A1 wild type and the triple mutant. Surprisingly the CYP102A2 and CYP102A3 from Bacillus subtilis did not show activity at all. Substrate binding spectra, recorded to investigate substrate accessibility to the enzyme’s active site, revealed that the substrates either could not access the active site of the Bacillus subtilis monooxygenases, or did not reach the heme proximity.Item Open Access Rapid quality assurance with requirements smells(2016) Femmer, Henning; Méndez Fernández, Daniel; Wagner, Stefan; Eder, SebastianContext: Bad requirements quality can cause expensive consequences during the software development lifecycle, especially if iterations are long and feedback comes late. Objectives: We aim at a light-weight static requirements analysis approach that allows for rapid checks immediately when requirements are written down. Method: We transfer the concept of code smells to Requirements Engineering as Requirements Smells. To evaluate the benefits and limitations, we define Requirements Smells, realize our concepts for a smell detection in a prototype called Smella and apply Smella in a series of cases provided by three industrial and a university context. Results: The automatic detection yields an average precision of 59% at an average recall of 82% with high variation. The evaluation in practical environments indicates benefits such as an increase of the awareness of quality defects. Yet, some smells were not clearly distinguishable. Conclusion: Lightweight smell detection can uncover many practically relevant requirements defects in a reasonably precise way. Although some smells need to be defined more clearly, smell detection provides a helpful means to support quality assurance in Requirements Engineering, for instance, as a supplement to reviews.Item Open Access Operationalised product quality models and assessment: the Quamoco approach(2015) Wagner, Stefan; Goeb, Andreas; Heinemann, Lars; Kläs, Michael; Lampasona, Constanza; Lochmann, Klaus; Mayr, Alois; Plösch, Reinhold; Seidl, Andreas; Streit, Jonathan; Trendowicz, AdamContext: Software quality models provide either abstract quality characteristics or concrete quality measurements; there is no seamless integration of these two aspects. Quality assessment approaches are, hence, also very specific or remain abstract. Reasons for this include the complexity of quality and the various quality profiles in different domains which make it difficult to build operationalised quality models. Objective: In the project Quamoco, we developed a comprehensive approach aimed at closing this gap. Method: The project combined constructive research, which involved a broad range of quality experts from academia and industry in workshops, sprint work and reviews, with empirical studies. All deliverables within the project were peer-reviewed by two project members from a different area. Most deliverables were developed in two or three iterations and underwent an evaluation. Results: We contribute a comprehensive quality modelling and assessment approach: (1) A meta quality model defines the structure of operationalised quality models. It includes the concept of a product factor, which bridges the gap between concrete measurements and abstract quality aspects, and allows modularisation to create modules for specific domains. (2) A largely technology-independent base quality model reduces the effort and complexity of building quality models for specific domains. For Java and C# systems, we refined it with about 300 concrete product factors and 500 measures. (3) A concrete and comprehensive quality assessment approach makes use of the concepts in the meta-model. (4) An empirical evaluation of the above results using real-world software systems showed: (a) The assessment results using the base model largely match the expectations of experts for the corresponding systems. (b) The approach and models are well understood by practitioners and considered to be both consistent and well suited for getting an overall view on the quality of a software product. The validity of the base quality model could not be shown conclusively, however. (5) The extensive, open-source tool support is in a mature state. (6) The model for embedded software systems is a proof-of-concept for domain-specific quality models. Conclusion: We provide a broad basis for the development and application of quality models in indus- trial practice as well as a basis for further extension, validation and comparison with other approaches in research.